Final answer:
Foam dressings are used to promote healing in stage 4 or unstable pressure injuries.
Step-by-step explanation:
The dressing used to promote healing in stage 4 or unstable pressure injuries is foam dressings. These dressings are designed to absorb exudate (fluid from the wound) while maintaining a moist environment, which is important for wound healing. Foam dressings can help protect the wound from contamination and promote the growth of new tissue.